Mask



FIG. 1 is a perspective view of the mask.

FIG. 2 is a top plan view of the mask.

FIG. 3 is a bottom plan view thereof.

FIG. 4 is a left side view thereof.

FIG. 5 is a right side view thereof.

FIG. 6 is a front elevational view thereof; and,

FIG. 7 is a rear elevational view thereof.

The broken lines showing in FIGS. 1-7 form no part of the claimed design. 

CLAIM The ornamental design for a mask, as shown and described. 